Late onset GM2 gangliosidosis presenting with motor neuron disease: An autopsy case

Adult‐onset GM2 gangliosidosis is very rare and only three autopsy cases have been reported up to now. We report herein an autopsy case of adult‐onset GM2 gangliosidosis. The patient developed slowly progressive motor neuron disease‐like symptoms after longstanding mood disorder and cognitive dysfunction. He developed gait disturbance and weakness of lower limbs at age 52 years. Because of progressive muscle weakness and atrophy, he became bed‐ridden at age 65. At age of 68, he died. His neurological findings presented slight cognitive disturbance, slight manic state, severe muscle weakness, atrophy of four limbs and no extrapyramidal signs and symptoms, and cerebellar ataxia. Neuropathologically, mild neuronal loss and abundant lipid deposits were noted in the neuronal cytoplasm throughout the nervous system, including peripheral autonomic neurons. The most outstanding findings were marked neuronal loss and distended neurons in the anterior horn of the spinal cord, which supports his clinical symptomatology of lower motor neuron disease in this case. The presence of lipofuscin, zebra bodies and membranous cytoplasmic bodies (MCB) and the increase of GM2 ganglioside by biochemistry led to diagnosis of GM2 gangliosidosis.